Electric power take-off pump control systems

ABSTRACT

A refuse vehicle includes a chassis, an energy storage device, a vehicle body, an electric power take-off system, and a hydraulic component. The energy storage device is supported by the chassis and is configured to provide electrical power to a prime mover. Activation of the prime mover selectively drives the refuse vehicle. The vehicle body is supported by the chassis, and includes an on-board receptacle for storing refuse therein. The electric power take-off system is positioned on the vehicle body, and includes an electric motor configured to drive a hydraulic pump to convert electrical power received from the energy storage device into hydraulic power. An amount of electrical power at least one of received by and provided to the electric motor is limited by a controller to control an output characteristic of the hydraulic pump. The hydraulic component is in fluid communication with the hydraulic pump and configured to operate using hydraulic power from the electric power take-off system.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 63/084,378, filed Sep. 28, 2020, the content of which is herebyincorporated by reference in its entirety.

BACKGROUND

Electric refuse vehicles (i.e., battery-powered refuse vehicles) includeone or more energy storage elements (e.g., batteries) that supply energyto an electric motor. The electric motor supplies rotational power tothe wheels of the refuse vehicle to drive the refuse vehicle. The energystorage elements can also be used to supply energy to vehiclesubsystems, like the lift system or the compactor.

SUMMARY

One exemplary embodiment relates to a refuse vehicle. The refuse vehicleincludes a chassis, an energy storage device, a vehicle body, anelectric power take-off system, and a hydraulic component. The energystorage device is supported by the chassis and is configured to provideelectrical power to a prime mover. Activation of the prime moverselectively drives the refuse vehicle. The vehicle body is supported bythe chassis, and includes an on-board receptacle for storing refusetherein. The electric power take-off system is positioned on the vehiclebody, and includes an electric motor configured to drive a hydraulicpump to convert electrical power received from the energy storage deviceinto hydraulic power. An amount of electrical power at least one ofreceived by and provided to the electric motor is limited by acontroller to control an output characteristic of the hydraulic pump.The hydraulic component is in fluid communication with the hydraulicpump and configured to operate using hydraulic power from the electricpower take-off system.

One exemplary embodiment relates to a refuse vehicle. The refuse vehicleincludes a chassis, an energy storage device, a vehicle body, anelectric power take-off system, a lifting system, and a compactor. Theenergy storage device is supported by the chassis and is configured toprovide electrical power to a prime mover. Activation of the prime moverselectively drives the refuse vehicle. The vehicle body is supported bythe chassis, and includes an on-board receptacle for storing refusetherein. The electric power take-off system is positioned on the vehiclebody, and includes an electric motor configured to drive a hydraulicpump to convert electrical power received from the energy storage deviceinto hydraulic power. The hydraulic pump is a swashplate-style variabledisplacement pump. An amount of electrical power at least one ofreceived by and provided to the electric motor is limited by acontroller to control an output characteristic of the hydraulic pump.The lifting system is movable relative to the on-board receptacle usinghydraulic power from the electric power take-off system. The compactoris positioned within the on-board receptacle and is movable within theon-board receptacle using hydraulic power from the electric powertake-off system.

One exemplary embodiment relates to a refuse vehicle. The refuse vehicleincludes a chassis, an energy storage device, a vehicle body, anelectric power take-off system, a controller, and a lifting system. Theenergy storage device is supported by the chassis and is configured toprovide electrical power to a prime mover. Activation of the prime moverselectively drives the refuse vehicle. The vehicle body is supported bythe chassis, and includes an on-board receptacle for storing refusetherein. The electric power take-off system is positioned on the vehiclebody, and includes an electric motor configured to drive aswashplate-style variable displacement hydraulic pump to convertelectrical power received from the energy storage device into hydraulicpower. The controller is configured to monitor a hydraulic fluid flowrate and a hydraulic fluid pressure downstream of the swashplate-stylevariable displacement hydraulic pump and adjust an output of theswashplate-style variable displacement hydraulic pump by adjusting anangle of a swashplate of the swashplate-style variable displacementhydraulic pump upon detecting that a product of the hydraulic fluid flowrate and the hydraulic fluid pressure exceed a threshold torque value.The lifting system is movable relative to the on-board receptacle usinghydraulic power from the electric power take-off system.

The invention is capable of other embodiments and of being carried outin various ways. Alternative exemplary embodiments relate to otherfeatures and combinations of features as may be recited herein.

BRIEF DESCRIPTION OF THE FIGURES

The disclosure will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingfigures, wherein like reference numerals refer to like elements, inwhich:

FIG. 1 is a perspective view of a front loading refuse vehicle accordingto an exemplary embodiment;

FIG. 2 is a perspective view of a side loading refuse vehicle accordingto an exemplary embodiment;

FIG. 3 is a front perspective view of an electric front loading refusevehicle according to an exemplary embodiment;

FIG. 4 is another perspective view of the electric front loading refusevehicle of FIG. 3 ;

FIG. 5 is a schematic view of a control system of the refuse vehicle ofFIG. 3 ;

FIG. 6 is a hydraulic circuit that can be incorporated into the controlsystem of FIG. 5 ;

FIG. 7 is a graphical representation of a pump performance curve,depicting different control parameters that can be incorporated into thepump within the control system of FIG. 5 ;

FIG. 8 is a graphical representation of a pump performance curve,depicting a hydraulic pump within the control system of FIG. 5 withouttorque limiting control; and

FIG. 9 is a graphical representation of a pump performance curve,depicting a hydraulic pump within the control system of FIG. 5 withtorque limiting control, according to an exemplary embodiment.

DETAILED DESCRIPTION

Before turning to the figures, which illustrate the exemplaryembodiments in detail, it should be understood that the presentapplication is not limited to the details or methodology set forth inthe description or illustrated in the figures. It should also beunderstood that the terminology is for the purpose of description onlyand should not be regarded as limiting.

Referring to the FIGURES generally, the various exemplary embodimentsdisclosed herein relate to electric refuse vehicles. Electric refusevehicles, or E-refuse vehicles, include an onboard energy storagedevice, like a battery, that provides power to a motor that producesrotational power to drive the vehicle. The energy storage device, whichis commonly a battery or assembly of batteries, can be used to providepower to different subsystems on the E-refuse vehicle. The energystorage device is also configured to provide hydraulic power todifferent subsystems on the E-refuse vehicle through an electric powertake-off (E-PTO) system. The E-PTO system receives electrical power fromthe energy storage device and provides the electrical power to anelectric motor. The electric motor drives a hydraulic pump that providespressurized hydraulic fluid to different vehicle subsystems, includingthe compactor and the lifting system.

The E-PTO system draws electrical power from the main battery of therefuse vehicle to drive the hydraulic pump. Because the E-PTO systemdraws electrical power from the same battery used to power the electricmotor that drives the refuse vehicle, a controller (e.g., a powerdistribution unit) monitors and meters the power delivery to the E-PTOsystem. By controlling the power draw of the E-PTO system, the refusevehicle can avoid a stalled condition that might otherwise occur fromover-torqueing the hydraulic pump. The controller ensures that even whenthe hydraulic pump of the E-PTO is being driven, adequate electricalpower is available from the battery to drive the refuse vehicle. Theinclusion of the torque-limiting controller allows the use of smaller,less expensive electrical motors with the E-PTO system.

Referring to FIGS. 1-4 , a vehicle, shown as refuse truck 10 (e.g.,garbage truck, waste collection truck, sanitation truck, etc.), includesa chassis, shown as a frame 12, and a body assembly, shown as body 14,coupled to the frame 12. The body assembly 14 defines and includes anon-board receptacle 16 and a cab 18. The cab 18 is coupled to a frontend of the frame 12, and includes various components to facilitateoperation of the refuse truck 10 by an operator (e.g., a seat, asteering wheel, hydraulic controls, etc.) as well as components that canexecute commands automatically to control different subsystems withinthe vehicle (e.g., computers, controllers, processing units, etc.). Therefuse truck 10 further includes a prime mover 20 coupled to the frame12 at a position beneath the cab 18. The prime mover 20 provides powerto a plurality of motive members, shown as wheels 21, and to othersystems of the vehicle (e.g., a pneumatic system, a hydraulic system,etc.). In one embodiment, the prime mover 20 is one or more electricmotors coupled to the frame 12. The electric motors may consumeelectrical power from an on-board energy storage device (e.g., batteries23, ultra-capacitors, etc.), from an on-board generator (e.g., aninternal combustion engine), or from an external power source (e.g.,overhead power lines) and provide power to the various systems of therefuse truck 10.

According to an exemplary embodiment, the refuse truck 10 is configuredto transport refuse from various waste receptacles within a municipalityto a storage or processing facility (e.g., a landfill, an incinerationfacility, a recycling facility, etc.). As shown in FIGS. 1-4 , the body14 and on-board receptacle 16, in particular, include a series ofpanels, shown as panels 22, a cover 24, and a tailgate 26. The panels22, cover 24, and tailgate 26 define a collection chamber 28 of theon-board receptacle 16. Loose refuse is placed into the collectionchamber 28, where it may be thereafter compacted. The collection chamber28 provides temporary storage for refuse during transport to a wastedisposal site or a recycling facility, for example. In some embodiments,at least a portion of the on-board receptacle 16 and collection chamber28 extend over or in front of the cab 18. According to the embodimentshown in FIGS. 1-4 , the on-board receptacle 16 and collection chamber28 are each positioned behind the cab 18. In some embodiments, thecollection chamber 28 includes a hopper volume 52 and a storage volume.Refuse is initially loaded into the hopper volume 52 and thereaftercompacted into the storage volume. According to an exemplary embodiment,the hopper volume is positioned between the storage volume and the cab18 (i.e., refuse is loaded into a position behind the cab 18 and storedin a position further toward the rear of the refuse truck 10).

Referring again to the exemplary embodiment shown in FIG. 1 , the refusetruck 10 is a front-loading refuse vehicle. As shown in FIG. 1 , therefuse truck 10 includes a lifting system 30 that includes a pair ofarms 32 coupled to the frame 12 on either side of the cab 18. The arms32 may be rotatably coupled to the frame 12 with a pivot (e.g., a lug, ashaft, etc.). In some embodiments, actuators (e.g., hydraulic cylinders,etc.) are coupled to the frame 12 and the arms 32, and extension of theactuators rotates the arms 32 about an axis extending through the pivot.According to an exemplary embodiment, interface members, shown as forks34, are coupled to the arms 32. The forks 34 have a generallyrectangular cross-sectional shape and are configured to engage a refusecontainer (e.g., protrude through apertures within the refuse container,etc.). During operation of the refuse truck 10, the forks 34 arepositioned to engage the refuse container (e.g., the refuse truck 10 isdriven into position until the forks 34 protrude through the apertureswithin the refuse container). As shown in FIG. 1 , the arms 32 arerotated to lift the refuse container over the cab 18. A second actuator(e.g., a hydraulic cylinder) articulates the forks 34 to tip the refuseout of the container and into the hopper volume of the collectionchamber 28 through an opening in the cover 24. The actuator thereafterrotates the arms 32 to return the empty refuse container to the ground.According to an exemplary embodiment, a top door 36 is slid along thecover 24 to seal the opening thereby preventing refuse from escaping thecollection chamber 28 (e.g., due to wind, etc.).

Referring to the exemplary embodiment shown in FIG. 2 , the refuse truck10 is a side-loading refuse vehicle that includes a lifting system,shown as a grabber 38 that is configured to interface with (e.g.,engage, wrap around, etc.) a refuse container (e.g., a residentialgarbage can, etc.). According to the exemplary embodiment shown in FIG.2 , the grabber 38 is movably coupled to the body 14 with an arm 40. Thearm 40 includes a first end coupled to the body 14 and a second endcoupled to the grabber 38. An actuator (e.g., a hydraulic cylinder 42)articulates the arm 40 and positions the grabber 38 to interface withthe refuse container. The arm 40 may be movable within one or moredirections (e.g., up and down, left and right, in and out, rotation,etc.) to facilitate positioning the grabber 38 to interface with therefuse container. According to an alternative embodiment, the grabber 38is movably coupled to the body 14 with a track. After interfacing withthe refuse container, the grabber 38 is lifted up the track (e.g., witha cable, with a hydraulic cylinder, with a rotational actuator, etc.).The track may include a curved portion at an upper portion of the body14 so that the grabber 38 and the refuse container are tipped toward thehopper volume of the collection chamber 28. In either embodiment, thegrabber 38 and the refuse container are tipped toward the hopper volumeof the collection chamber 28 (e.g., with an actuator, etc.). As thegrabber 38 is tipped, refuse falls through an opening in the cover 24and into the hopper volume of the collection chamber 28. The arm 40 orthe track then returns the empty refuse container to the ground, and thetop door 36 may be slid along the cover 24 to seal the opening therebypreventing refuse from escaping the collection chamber 28 (e.g., due towind).

Referring to FIGS. 3-4 , the refuse truck 10 is a front loading E-refusevehicle. Like the refuse truck 10 shown in FIG. 1 , the E-refuse vehicleincludes a lifting system 30 that includes a pair of arms 32 coupled tothe frame 12 on either side of the cab 18. The arms 32 are rotatablycoupled to the frame 12 with a pivot (e.g., a lug, a shaft, etc.). Insome embodiments, actuators (e.g., hydraulic cylinders, etc.) arecoupled to the frame 12 and the arms 32, and extension of the actuatorsrotates the arms 32 about an axis extending through the pivot. Accordingto an exemplary embodiment, interface members, shown as forks 34, arecoupled to the arms 32. The forks 34 have a generally rectangularcross-sectional shape and are configured to engage a refuse container(e.g., protrude through apertures within the refuse container, etc.).During operation of the refuse truck 10, the forks 34 are positioned toengage the refuse container (e.g., the refuse truck 10 is driven intoposition until the forks 34 protrude through the apertures within therefuse container). A second actuator (e.g., a hydraulic cylinder)articulates the forks 34 to tip the refuse out of the container and intothe hopper volume of the collection chamber 28 through an opening in thecover 24. The first actuators thereafter rotate the arms 32 to returnthe empty refuse container to the ground. According to an exemplaryembodiment, a top door 36 is slid along the cover 24 to seal the openingthereby preventing refuse from escaping the collection chamber 28 (e.g.,due to wind, etc.).

Still referring to FIGS. 3-4 , the refuse truck 10 includes one or moreenergy storage devices, shown as batteries 23. The batteries 23 can berechargeable lithium-ion batteries, for example. The batteries 23 areconfigured to supply electrical power to the prime mover 20, whichincludes one or more electric motors. The electric motors are coupled tothe wheels 21 through a vehicle transmission, such that rotation of theelectric motor (e.g., rotation of a drive shaft of the motor 20) rotatesa transmission shaft, which in turn rotates the wheels 21 of thevehicle. In other examples, one or more wheels 21 have dedicated anddirect-drive electric motors, such that the transmission can be omitted.The batteries 23 can supply electrical power to additional subsystems onthe refuse truck 10, including additional electric motors, cab controls(e.g., climate controls, steering, lights, etc.), the lifting system 30,and/or the compactor 50, for example.

The refuse truck 10 can be considered a hybrid refuse vehicle as itincludes both electric and hydraulic power systems. As depicted in FIGS.3-5 , the refuse truck 10 includes an E-PTO system 100. The E-PTO system100 is configured to receive electrical power from the batteries 23 andconvert the electrical power to hydraulic power. In some examples, theE-PTO system 100 includes an electric motor 104 driving a hydraulic pump102. The hydraulic pump 102 pressurizes hydraulic fluid onboard therefuse truck 10, which can then be supplied to various hydrauliccomponents (e.g., hydraulic cylinders and other actuators, etc.)provided as part of the refuse truck 10. For example, the hydraulic pump102 can provide pressurized hydraulic fluid to each of the hydrauliccylinders within the lift system 30 on the refuse truck. Additionally oralternatively, the hydraulic pump 102 can provide pressurized hydraulicfluid to a hydraulic cylinder or hydraulic cylinders controlling thecompactor 50. In some embodiments, the hydraulic pump 102 also providespressurized hydraulic fluid to the hydraulic cylinders that control aposition and orientation of the tailgate 26. The hydraulic pump 102 canbe a swashplate-type variable displacement pump, for example.

With continued reference to FIG. 5 , the refuse truck 10 can include adisconnect 200 positioned between the one or more batteries 23 and theE-PTO system 100. The disconnect 200 provides selective electricalcommunication between the batteries 23 and the E-PTO system 100 that canallow the secondary vehicle systems (e.g., the lift system, compactor,etc.) to be decoupled and de-energized from the electrical power source.The disconnect 200 can create an open circuit between the batteries 23and the E-PTO system 100, such that no electricity is supplied from thebatteries 23 to either of the electric motor 104 or an inverter 110 thatis coupled to the electric motor 104 to convert DC power from thebatteries 23 to AC power for use in the electric motor 104. Withoutelectrical power from the batteries 23, the electric motor 104 will notdrive the hydraulic pump 102. Pressure within the hydraulic system willgradually decrease, such that none of the lifting system 30, compactor50, or vehicle subsystems 106 relying upon hydraulic power will be fullyfunctional. The refuse truck 10 can then be operated in a lower powerconsumption mode, given the reduced electrical load required from thebatteries 23 to operate the refuse truck 10. The disconnect 200 furtherenables the refuse truck 10 to conserve energy when the vehiclesubsystems are not needed, and can also be used to lock out the variousvehicle subsystems to perform maintenance activities.

The disconnect 200 further allows an all-electric vehicle chassis to beretrofit with hydraulic power systems, which can be advantageous for avariety of reasons, as hydraulic power systems may be more responsiveand durable than fully electric systems. In some examples, the E-PTOsystem 100 includes a dedicated secondary battery 108 that is configuredto supply electrical power to the E-PTO system 100 if the disconnect 200is tripped, such that the secondary vehicle systems can remain optionaleven when the E-PTO system 100 is not receiving electrical power fromthe batteries 23. In some examples, the E-PTO system 100 operatesindependently of the battery 23, and includes its own dedicatedsecondary battery 108 that supplies DC electrical power to the inverter110. The inverter 110 converts the DC electrical power to AC electricalpower that can then be supplied to the electric motor 104. In stillfurther embodiments, the dedicated secondary battery 108 is directlycoupled to the electric motor 104 and supplies DC electrical powerdirectly to the electric motor 104. With the secondary battery 108present within the E-PTO system 100, the E-PTO system can be agnostic tothe chassis type, and can be incorporated into all-electric, hybrid,diesel, CNG, or other suitable chassis types.

The E-PTO system 100 can include one or more thermal management systemsor devices to alleviate heat generated by the E-PTO system 100. In someexamples, the E-PTO system 100 includes a radiator 112. The radiator 112can be a water-cooled heat exchanger that is configured to remove heatgenerated by the inverter 110, electric motor 104, and hydraulic pump102 of the E-PTO system 100. In some examples, the radiator 112 drawspower from the battery 23. Alternatively, the radiator 112 can bepowered by the secondary battery 108 directly or through the inverter110. In some examples, the E-PTO system 100 includes one or more fans tofacilitate heat removal from the components within the E-PTO system 100.

In some examples, the battery 23 includes a controller, shown as powerdistribution unit (PDU) 114. The PDU 114 monitors the battery 23 andcontrols contactors within the battery 23 (or within associatedequipment) to direct electrical power to the various systems within therefuse truck 10. In some examples, the PDU 114 prioritizes electricalpower delivery through the refuse truck 10. The PDU 114 can ensure thatcritical functions (e.g., the prime mover 20, etc.) receive electricalpower before auxiliary systems, like the E-PTO system 100, climatecontrol systems, or radio, for example. Additionally or alternatively,the PDU 114 can be included within the E-PTO system 100 to controlbattery power draw from the battery 23 by the E-PTO system 100 (e.g.,through the disconnect 200). In some examples, the PDU 114 can beconfigured to limit the permissible power draw from the battery 23 bythe E-PTO system 100, which serves to limit the torque drawn by thehydraulic pump 102. The PDU 114 can be in communication with acontroller 120, as described in additional detail below.

As discussed previously, the hydraulic pump 102 can be one or moreswashplate-style variable displacement pumps. Although describedsingularly throughout, the term “pump” should be considered to includeone or more pumps. In some examples, and as shown in FIG. 6 , the E-PTOsystem 100 incorporates a torque-limiting hydraulic circuit 202 tocontrol operation of the pump 102 so that over-torqueing and potentiallyharmful stall conditions are avoided and power draw from the battery 23is limited. The pump 102 is configured to provide pressurized hydraulicfluid from the hydraulic fluid reservoir 204 to the actuators (i.e.,hydraulic cylinders) within the lifting system 30 to manipulate aposition or orientation of the arms 32 and/or the forks 34, for example.The pump 102 can also supply pressurized hydraulic fluid from thehydraulic fluid reservoir 204 to a packer/compactor 50 and ejectorsystem positioned within the on-board receptacle 16. In the schematicdepicted in FIG. 6 , the pump load 206 can represent any combination ofone or more of the various actuators within the refuse truck 10 that arepowered by the E-PTO system 100.

The pump 102 and electric motor 104 driving the pump 102 are incommunication with a processing unit, shown as the controller 120. Thecontroller 120 at least partially controls the pump 102 and electricmotor 104 to deliver pressurized hydraulic fluid to accommodate variablepump loads 206 that may be requested during normal refuse truck 10operation. The controller 120 receives signals from various inputsthroughout the refuse truck 10 and can subsequently control differentcomponents within the hydraulic circuit 202 to execute different tasks.For example, the controller 120 may receive an input from one or morebuttons within the cab 18 of the refuse truck 10 that prompt the liftingsystem 30 to move in order to raise and empty the contents of a wastereceptacle into the on-board receptacle 16 of the refuse truck 10. Uponreceiving an input requesting an adjustment of the pump load 206 (e.g.,requested movement of the lifting system 30), the controller 120 canactivate or adjust an output of the electric motor 104 and pump 102 todeliver pressurized hydraulic fluid from the hydraulic fluid reservoir204 to the one or more actuators forming the pump load 206 to carry outthe requested operation.

A sensor 210 positioned within the hydraulic circuit 202 can monitor apressure and/or a flow rate of hydraulic fluid downstream of the pump102 to determine a current pump flow rate and/or the pressure ofhydraulic fluid being output by the pump 102. Another sensor 212 coupledto the pump 102 can measure a current angle of a swashplate 208 on thepump 102, which corresponds to a current pump 102 displacement. In someexamples, the controller 120 receives data from each of the sensors 210,212 and, using the data received form the sensors 210, 212, determinesan appropriate adjustment to the angle of the swashplate 208 to meet thenew requested pump load 206 corresponding with the input received (e.g.,to execute a compactor or ejection stroke or lift a waste receptaclewith the lifting system 30) by the controller 120. The controller 120then adjusts the swashplate 208 angle in order to arrive at theswashplate angle that was determined by the PDU 114 so that the pump 102can efficiently deliver the desired pump flow or fluid pressureassociated with the requested pump load 206. In some examples, thecontroller 120 communicates with the PDU 114 to request a power drawfrom the battery 23 to meet the desired pump conditions.

The hydraulic circuit 202 includes a series of valves and pressure linesthat are configured to direct pressurized hydraulic fluid between thehydraulic fluid reservoir 204, the pump 102, and the load 206 to executeoperations with the various actuators on the refuse truck 10. The valvesand pressure lines are arranged so that the hydraulic circuit 202 isdivided into a high pressure line 220, an intermediate pressure or“control” line 222, and a low pressure or “drain” line 224. One or morevalves 226, 228, 230, 232 are positioned between the lines 220, 222, 224and selectively provide fluid communication between the lines 220, 222,224 to control operation of the pump 202 and distribute hydraulic fluidto the various actuators within the pump load 206. As depicted in FIG. 6, the valves 226, 228, 230 can each be spool valves that include severalpositions that define different flow paths through the valves 226, 228,230. The valve 232 can be a solenoid valve that is adjustable throughmultiple positions to control fluid flow rate through the hydrauliccircuit 202. In some examples, the valve 226 acts as a load sensingvalve that monitors pressure drop within the hydraulic circuit 202 andoperates to maintain a constant fluid flow rate through the valve 226.The valve 228 can act as a compensator valve that opens a pressurerelief fluid pathway through the valve 228 when pressure within thehydraulic circuit 202 rises above a threshold level (e.g., a cutoutpressure). The valve 230 can act as a torque limiting or torque reducingvalve that adjusts a pump flow rate when hydraulic pressure within thehigh pressure line 220 exceeds a threshold valve. Similarly, the valve232 can provide torque limiting control. The valve 232 can be controlledby the controller 120 to activate in response to a detected fluidpressure above a threshold rate, which may be determined by a pumptorque limiting control curve, as explained in additional detail below.

During normal operation, and as depicted in FIG. 6 , each of the valves226, 228, 230, 232 are biased into their first open positions. In thefirst open position, each of the valves 226, 228, 230, 232 allowhydraulic fluid flow into and through the valves 226, 228, 230, 232. Thevalves 226, 228, 230, 232 can each be biased into their first positionsby biasing elements, shown as springs 234, 236, 238, 240. The springs234, 236, 238, 240 provide a spring force that opposes movement of thevalves 226, 228, 230, 232 away from their respective first openpositions toward intermediate closed positions or to second openpositions. The valves 226, 228, 230, 232 can each be placed in fluidcommunication with the high pressure line 220. Fluid pressure within thehigh pressure line 220 can act against the springs 234, 236, 238 to movethe valves toward their respective intermediate closed or second openpositions. The valve 232 is controlled by a solenoid actuator that canbe energized by the controller 120 and/or the PDU 114, for example.

When the controller 120 initially receives or otherwise generates aninput to adjust the pump load 206 (e.g., to provide pressurizedhydraulic fluid to an actuator), the pump 102 begins to operate todeliver the requested pump load 206 from the hydraulic fluid reservoir204. Hydraulic fluid is drawn from the hydraulic fluid reservoir 204into the pump 202 along a first branch 242. The fluid is pressurizedwithin the pump 102 and directed outward along a first branch 244 of thehigh pressure line 220. The pressurized hydraulic fluid is deliveredthrough the first branch 244 to the pump load 206, which expands andextends the actuators so that the actuators can execute the variousfunctions inputted to the controller 120. As depicted in FIG. 6 ,hydraulic fluid inputted through the first branch 244 into the actuatorreservoir 246 pushes a piston 248 of the pump load 206 outward andextends the one or more actuators within the pump load 206.

As discussed above, the pump 102 is a swashplate-type variabledisplacement pump. The pump 102 includes at least two pistons thatoperate to compress fluid. The stroke length of the pistons, which isdetermined by the angle of the swashplate 208, determines thedisplacement (e.g., flow rate) of hydraulic fluid that exits the pump102. Because the sensor 212 monitors the position (e.g., the angle) ofthe swashplate 208, the sensor 212 can effectively serve as a flow ratesensor. By communicating the monitored position of the swashplate 208 tothe controller 120, the controller 120 can then determine (e.g.,calculate or access from a table of values) the flow rate (Q) out of thepump 102. The sensor 212 can be a mechanical position sensor (e.g., anencoder or an LVDT).

The sensor 210 can be used to monitor other characteristics of pumpoperation by monitoring the pressurized hydraulic fluid within the highpressure line 220. The sensor 210 is positioned along the first branch244 of the high pressure line 220 to monitor one or more pumpparameters. For example, the sensor 210 can monitor the hydraulic fluidpressure within the high pressure line 220. By being located justdownstream of the pump 102, the sensor 210 provides a near real-timemeasurement of pump output. Using the measured hydraulic fluid pressurewithin the high pressure line 220 and the measured orientation of theswashplate 208 to determine the flow rate through the pump 102, thecontroller 120 can calculate the torque experienced by (and required todrive) the electric motor 104 that drives the pump 102. The torque (T)experienced by the motor of the pump 102 is the product of the pumppressure (P) and the flow rate (Q) through the pump 102 (i.e., T=P*Q).The calculated torque corresponds to the amount of electric power drawfrom the battery 23 to achieve the desired pump parameters.

The pump 102 is configured to provide pressurized hydraulic fluid fromthe hydraulic fluid reservoir 204 to multiple actuators that togetherdefine the pump load 206. In some instances, the pump load 206 mayexceed the allowable pressure or flow rate that the pump 102 canproduce. For example, if the lifting system 30 is attempting to raise aheavy waste receptacle while the compactor system 50 is executing acompactor stroke within the on-board receptacle 16, further expansion ofthe hydraulic cylinders may be opposed. The resistance provided by themass of the heavy waste receptacle and the refuse within thereceptacle's 16 resistance to packing can oppose further movement of thehydraulic cylinders attempting to perform the lifting and compactingfunctions, respectively. Because the flow rate of the pump 102 does notchange (e.g., the amount of hydraulic fluid necessary to move the piston248 to a desired position within the actuator reservoir 246 remainsconstant), the resistance to movement causes a pressure spike within thefirst branch 244 of the high pressure line 220. With the flow rate (Q)remaining constant, the pressure spike (P) within the first branch 244of the high pressure line 220 causes a subsequent spike in torqueexperienced by the pump motor 104 and power draw requested by the E-PTOsystem 100 from the battery 23.

If the torque experienced by the electric motor 104 approaches orexceeds the amount of torque that the electric motor 104 can produce,the electric motor 104 will slow or stall and potentially burn out. Toavoid these potentially fatal motor conditions, the valve 232 isarranged to override the hydraulic circuit 202 and control the pump 102when the torque draw from the electric motor 104 exceeds a set thresholdlimit defined by the controller 120. The valve 232 controls flow betweenthe high pressure line 220 and the intermediate control line 222, whichin turn controls the angle of the swashplate 208 and the displacement ofthe pump 102. Opening the valve 232 further will increase the flowthrough the intermediate control line 222, which will drop thedisplacement of the pump 102 and reduce the likelihood of stalling thepump 102 and/or electric motor 104 of the E-PTO system 100.

The valve 232 is also used to control and limit the amount of allowabletorque drawn from the battery 23 so that primary vehicle systems (e.g.,the prime mover 20) can be supplied with sufficient power to drive therefuse truck 10 at all times. The controller 120 and/or the PDU 114 canbe programmed with a pump torque control curve (e.g., pump control curve308, shown in FIG. 7 ) that defines permissible flow rate and pressuretarget limits for the pump 102 and motor 104. The controller 120 cancontrol a position of the valve 232 to adjust flow through the valve232, which in turn adjusts the pressure within the control line 222. Thepressure within the control line 222 controls the amount of forceapplied to the swashplate 208 against the bias of a spring 216.Accordingly, opening or closing the valve 232 adjusts an angle of theswashplate 208 and displacement of the variable displacement pump 102,which in turn adjusts an amount of torque draw requested by the pump 102and electrical motor 104. The controller 120 can communicate with thesensors 210, 212 to ensure that the pump 102 and electrical motor 104 donot exceed the allowable torque limits.

The controller 120 and/or the PDU 114 can be programmed to operate theelectric motor 104 and the pump 102 of the E-PTO system 100 according tospecified torque limits that restrict the permissible power draw of theelectric motor 104 from the battery 23. Referring to FIG. 7 , an examplepump performance control curve for the hydraulic pump 102 is shown. Asexplained above, pump torque is a function of pressure multiplied byflow rate, and determines how much power is needed from the battery 23to execute a function. A first curve 302 demonstrates the performance ofa first non-limited hydraulic pump 102 that is operated independent of(or without) the PDU 114 and/or the controller 120. The curve 302extends linearly over a first range of pressures and flow rates untilreaching a maximum flow rate. As the pressure continues to rise withinthe pump 102, the pressure and flow rate eventually reach a stallingtorque at point 304. At the stalling torque, the pump 102 ceases andboth pressure and flow rate through the pump drop to zero. Accordingly,the torque will also fall to zero.

The second curve 306 demonstrates the operation of the same hydraulicpump 102, but operating within a torque-limiting setting defined by thePDU 114 or the controller 120 (in the battery 23 or within the E-PTOsystem 100). The controller 120 defines a torque limiting curve 308,which constrains the pump performance to minimize the electrical powerdraw of the electric motor 104 from the battery 23. As the pumpapproaches a certain pressure (e.g., 15 MPa), the pump reaches thetorque limiting control curve 308. The controller 120 then monitors thepump performance (e.g., using sensors 210, 212) so as not to exceed thedefined limits established by the control curve 308. To remain withinthe parameters of acceptable operation, the controller 120 will adjust aposition of the valve 232 to reduce the flow rate through the pump 102as the pressure rises, which in turn reduces the torque and power drawrequired to operate the hydraulic pump 102. By limiting the possiblepump 102 input torque, the controller 120 ensures that power consumptionby the E-PTO system 100 does not exceed allowable limits that mightotherwise interfere with the ability to drive the vehicle 10, forexample. Additionally, smaller, less expensive electric motors 104 canbe used within the E-PTO system 100 because the battery 23 does not needto supply power under maximum pump output operating conditions, whichare disabled. Finally, the pump 102 can be operated within its mostefficient ranges.

Different control curves 308, 310 can be used and adapted for differentpump sizes and applications. As demonstrated in FIG. 7 , a control curve310 can be designed for a smaller pump 102 as well. The non-limitedcurve 312 of the smaller capacity pump 102 can be configured with areduced control curve 310 that again reduces the permissible power drawfrom the battery 23, which again reduces the power draw for the E-PTOsystem and prioritizes primary vehicle functions. The curve 314 followsthe limited torque curve 310 for a smaller pump, demonstrating thedifferent potential controlling parameters, depicting limit-basedcontrol, rather than target-based control.

As depicted in FIGS. 8-9 , the use of the torque limiting control curvewithin the controller 120 and the E-PTO system 100 can reduce the amountof power drawn from the battery 23. FIG. 8 depicts a pump motor torquecurve 400 of a pump 102 without a torque limiting valve 232 andcontroller 120 described above, while FIG. 9 and pump motor torque curve402 depicts the same pump with the torque limiting valve 232 andcontroller 120. While the overall operating range 404 of the motor 104and the pump 102 is slightly reduced, the pump 102 avoids maximum outputtorque conditions that could otherwise affect the operation of therefuse truck 10. By limiting permissible torque draw from the battery 23and limiting the possible flow characteristics of the pump 102, smaller,less expensive and more efficient motors 104 can be used with the E-PTO,which reduces packaging size, weight, and cost in producing the refusetruck 10.

Using the previously described systems and methods, a refuse truck canbe effectively outfitted with an E-PTO system that can convertelectrical power to hydraulic power to provide pressurized hydraulicfluid to various subsystems on the vehicle. The E-PTO system can bepackaged and retrofit onto existing refuse trucks and can beincorporated into various different vehicle chassis types. The E-PTOsystem can be powered by an auxiliary or self-contained power source, orcan draw power from the main battery of the vehicle. The E-PTO systemincludes a torque limiting controller and valve that together regulate apump of the E-PTO so that the power draw from the main battery of therefuse truck is maintained below a threshold value that ensures criticalvehicle functions can continue to be performed. Smaller and lessexpensive motors can be incorporated into the E-PTO system to achievethe same or similar permissible pump parameters that do not exceed theallowable torque limits set by the controller and valve.

Although the description of the E-PTO system and disconnect have beendescribed within the context of a front end loading refuse truck, thesame or similar systems can also be included in both side loading andrear end loading refuse trucks without significant modification.Accordingly, the disclosure should be considered to encompass the E-PTOsystem and pump in isolation and incorporated into any type or variationof refuse vehicle. Additionally, as described above, multipletorque-limited pumps may be incorporated into a single E-PTO systemwithout departing from the scope of the present disclosure.

Although this description may discuss a specific order of method steps,the order of the steps may differ from what is outlined. Also two ormore steps may be performed concurrently or with partial concurrence.Such variation will depend on the software and hardware systems chosenand on designer choice. All such variations are within the scope of thedisclosure. Likewise, software implementations could be accomplishedwith standard programming techniques with rule-based logic and otherlogic to accomplish the various connection steps, processing steps,comparison steps, and decision steps.

As utilized herein, the terms “approximately”, “about”, “substantially”,and similar terms are intended to have a broad meaning in harmony withthe common and accepted usage by those of ordinary skill in the art towhich the subject matter of this disclosure pertains. It should beunderstood by those of skill in the art who review this disclosure thatthese terms are intended to allow a description of certain featuresdescribed and claimed without restricting the scope of these features tothe precise numerical ranges provided. Accordingly, these terms shouldbe interpreted as indicating that insubstantial or inconsequentialmodifications or alterations of the subject matter described and claimedare considered to be within the scope of the invention as recited in theappended claims.

It should be noted that the term “exemplary” as used herein to describevarious embodiments is intended to indicate that such embodiments arepossible examples, representations, and/or illustrations of possibleembodiments (and such term is not intended to connote that suchembodiments are necessarily extraordinary or superlative examples).

The terms “coupled,” “connected,” and the like, as used herein, mean thejoining of two members directly or indirectly to one another. Suchjoining may be stationary (e.g., permanent, etc.) or moveable (e.g.,removable, releasable, etc.). Such joining may be achieved with the twomembers or the two members and any additional intermediate members beingintegrally formed as a single unitary body with one another or with thetwo members or the two members and any additional intermediate membersbeing attached to one another.

References herein to the positions of elements (e.g., “top,” “bottom,”“above,” “below,” “between,” etc.) are merely used to describe theorientation of various elements in the figures. It should be noted thatthe orientation of various elements may differ according to otherexemplary embodiments, and that such variations are intended to beencompassed by the present disclosure.

It is important to note that the construction and arrangement of therefuse truck as shown in the exemplary embodiments is illustrative only.Although only a few embodiments of the present disclosure have beendescribed in detail, those skilled in the art who review this disclosurewill readily appreciate that many modifications are possible (e.g.,variations in sizes, dimensions, structures, shapes and proportions ofthe various elements, values of parameters, mounting arrangements, useof materials, colors, orientations, etc.) without materially departingfrom the novel teachings and advantages of the subject matter recited.For example, elements shown as integrally formed may be constructed ofmultiple parts or elements. It should be noted that the elements and/orassemblies of the components described herein may be constructed fromany of a wide variety of materials that provide sufficient strength ordurability, in any of a wide variety of colors, textures, andcombinations. Accordingly, all such modifications are intended to beincluded within the scope of the present inventions. Othersubstitutions, modifications, changes, and omissions may be made in thedesign, operating conditions, and arrangement of the preferred and otherexemplary embodiments without departing from scope of the presentdisclosure or from the spirit of the appended claims.

What is claimed is:
 1. A refuse vehicle comprising: a chassis; an energystorage device supported by the chassis and configured to provideelectrical power to a prime mover, wherein activation of the prime moverselectively drives the refuse vehicle; a vehicle body supported by thechassis, the vehicle body including an on-board receptacle for storingrefuse therein; an electric power take-off system positioned on thevehicle body, the electric power take-off system including an electricmotor configured to drive a hydraulic pump to convert electrical powerreceived from the energy storage device into hydraulic power, wherein anamount of electrical power at least one of received by and provided tothe electric motor is limited by a controller to control an outputcharacteristic of the hydraulic pump; and a hydraulic component in fluidcommunication with the hydraulic pump and configured to operate usinghydraulic power from the electric power take-off system, wherein thehydraulic pump is a swashplate-style variable displacement pump, andwherein the controller controls the output characteristic of thehydraulic pump by activating a solenoid valve, wherein activating thesolenoid valve selectively opens a flow path to introduce pressurizedhydraulic fluid toward a swashplate of the hydraulic pump to adjust anangle of the swashplate.
 2. The refuse vehicle of claim 1, whereinadjusting the angle of the swashplate using pressurized fluid adjusts aflow rate of the hydraulic pump, wherein adjusting the flow rate of thehydraulic pump reduces an amount of electrical power needed to drive thehydraulic pump.
 3. The refuse vehicle of claim 1, wherein adjusting theangle of the swashplate using pressurized fluid adjusts a dischargepressure of the hydraulic pump, wherein adjusting the discharge pressureof the hydraulic pump reduces an amount of electrical power needed todrive the hydraulic pump.
 4. The refuse vehicle of claim 1, wherein thesolenoid valve is biased toward a flow blocking position, wherein a flowpath between an outlet of the hydraulic pump and the swashplate isobstructed by the solenoid valve in the flow blocking position.
 5. Therefuse vehicle of claim 4, wherein when the solenoid valve is activated,the solenoid valve transitions to an open position fluidly coupling theoutlet of the hydraulic pump with the swashplate.
 6. The refuse vehicleof claim 1, wherein the controller limits a rate of electrical powerdrawn from the energy storage device by reducing an amount of torqueexperienced by the hydraulic pump.
 7. The refuse vehicle of claim 1,wherein the controller monitors a position of the swashplate using asensor, wherein the controller is configured to calculate a hydraulicfluid flow rate from the hydraulic pump based upon the monitoredposition of the swashplate, and wherein the controller is configured toactivate the solenoid valve in response to determining that thehydraulic fluid flow rate exceeds a threshold flow rate.
 8. The refusevehicle of claim 7, wherein the controller monitors a fluid pressuredownstream of an outlet of the hydraulic pump using a pressure sensor,and wherein the controller is configured to activate the solenoid valvein response to receiving an indication that a product of the hydraulicfluid flow rate and the fluid pressure exceed a threshold torque value.9. The refuse vehicle of claim 8, wherein the controller is programmedwith a pump torque curve, and wherein the controller is configured toadjust the position of the swashplate to adjust the hydraulic fluid flowrate of the hydraulic pump to remain below the pump torque curve. 10.The refuse vehicle of claim 1, further comprising a compactor positionedwithin the on-board receptacle, wherein the compactor is movable withinthe on-board receptacle using hydraulic power from the electric powertake-off system.
 11. The refuse vehicle of claim 1, further comprising adisconnect positioned between the energy storage device and the electricpower take-off system, wherein the disconnect is configured toselectively decouple the electric power take-off system from the energystorage device to disable the hydraulic pump.
 12. A refuse vehiclecomprising: a chassis; an energy storage device supported by the chassisand configured to provide electrical power to a prime mover, whereinactivation of the prime mover selectively drives the refuse vehicle; avehicle body supported by the chassis, the vehicle body including anon-board receptacle for storing refuse therein; an electric powertake-off system positioned on the vehicle body, the electric powertake-off system including an electric motor configured to drive ahydraulic pump to convert electrical power received from the energystorage device into hydraulic power, wherein an amount of electricalpower at least one of received by and provided to the electric motor islimited by a controller to control an output characteristic of thehydraulic pump, and wherein the hydraulic pump is a swashplate-stylevariable displacement pump; a lifting system movable relative to theon-board receptacle using hydraulic power from the electric powertake-off system; and a compactor positioned within the on-boardreceptacle and movable within the on-board receptacle using hydraulicpower from the electric power take-off system, wherein the controllercontrols the output characteristic of the hydraulic pump by activating asolenoid valve, wherein activating the solenoid valve selectively opensa flow path to introduce pressurized hydraulic fluid toward a swashplateof the hydraulic pump to adjust an angle of the swashplate.
 13. Therefuse vehicle of claim 12, wherein adjusting the angle of theswashplate using pressurized fluid adjusts a flow rate of the hydraulicpump, wherein adjusting the flow rate of the hydraulic pump reduces anamount of electrical power needed to drive the hydraulic pump.
 14. Therefuse vehicle of claim 13, wherein the controller monitors a positionof the swashplate using a sensor, wherein the controller is configuredto calculate a hydraulic fluid flow rate from the hydraulic pump basedupon the monitored position of the swashplate, and wherein thecontroller is configured to activate the solenoid valve in response todetermining that the flow rate exceeds a threshold flow rate.
 15. Therefuse vehicle of claim 14, wherein the controller monitors a fluidpressure downstream of an outlet of the hydraulic pump using a pressuresensor, and wherein the controller is configured to activate thesolenoid valve in response to receiving an indication that a product ofthe hydraulic fluid flow rate and the fluid pressure exceed a thresholdtorque value.
 16. The refuse vehicle of claim 15, wherein the thresholdtorque value is defined by a pump torque curve that is programmed intothe controller.
 17. A refuse vehicle comprising: a chassis; an energystorage device supported by the chassis and configured to provideelectrical power to a prime mover, wherein activation of the prime moverselectively drives the refuse vehicle; a vehicle body supported by thechassis, the vehicle body including an on-board receptacle for storingrefuse therein; an electric power take-off system positioned on thevehicle body, the electric power take-off system including an electricmotor configured to drive a swashplate-style variable displacementhydraulic pump to convert electrical power received from the energystorage device into hydraulic power; a controller configured to monitora hydraulic fluid flow rate and a hydraulic fluid pressure downstream ofthe swashplate-style variable displacement hydraulic pump and adjust anoutput of the swashplate-style variable displacement hydraulic pump byadjusting an angle of a swashplate of the swashplate-style variabledisplacement hydraulic pump upon detecting that a product of thehydraulic fluid flow rate and the hydraulic fluid pressure exceed athreshold torque value; and a lifting system movable relative to theon-board receptacle using hydraulic power from the electric powertake-off system.